I think I worked most of the kinks out, it just needs fine tuning. Don't tax yourself too much, there is a good chance the party wizard won't even read the book this spell is found in (he has some crazy ideas about books found in evil temples bound in human flesh being dangerous...). Anyway here it is:

Disrupt Elemental
Necromancy
Level: Wiz 3/Sorc 3
Components: V, S, M
Casting Time: 1 Standard Action
Range: Medium 100 ft + 10 ft per level
Effect: Ray
Duration: Instantaneous (or 1 round)
Saving Throw: Fortitude Partial (see text)
Spell Resistance: Yes

You shoot a ray of necromantic power to disrupt the elemental forces within an elemental creature, doing 1d6 damage per caster level (max 10d6). In addition the effected creature must succeed in a Fortitude save or be stunned for 1 round. The elemental subtype effected by this spell must be chosen when the spell is prepared, unless the caster is a sorcerer, in which the subtype is chosen upon casting.

Material Component: A pinch of grave dirt (for the Earth version), a vial of befouled water (for the Water version), a vial of swamp gas (for the Air version), or a piece of deadwood burned during the casting (for the Fire version).

Edit: Changed to make the spell able to effect the creatures it was made for.

Edit: Yea, ok the spell is not evil any more.

Edit: Decided on a Material Component, thanks everyone!